In order to measure the walking or jogging distance covered by a user, both mechanical and electronic pedometers have been developed. Typically, such pedometers are worn on the side of the user such as by being clipped to a belt or the waist line of the user's pants in the manner of a pager or the like. Other known pedometers are built into a wrist watch worn on the user's wrist. In general, the pedometer functions to record the distance covered by the user by responding to the user's body motion at each step. Pedometers include various features and functions such that they can be adapted to the personal stride of the user. The pedometer includes a display, such as an LCD or LED display, for displaying the distance covered, number of steps taken during the workout, stopwatch and clock features, etc.
In most cases, the known pedometers use a mechanical sensing device to respond to the user's body motion at each step. However, the use of the mechanical sensor is disadvantageous as it is more susceptible to breakage and inaccuracies.
Electronic pedometers are also known which include an electronic sensor circuit to respond to the user's body motion at each step or stride. These electronic pedometers are more reliable and less susceptible to breakage.
While the known pedometers provide useful information during a workout, they unfortunately do not provide the user with any indication as to the level of exertion being placed on the user's body. Thus, while specific performance limitations may be indicated, the pedometer cannot inform the user whether they are training to hard or to little. The user therefore needs some indication of the degree of physical effort actually exerted as measured by physiological signs. The use of physiological signs provides a more direct indication to guide the exercise than the information provided by the known pedometers such as the distance travelled, amount of time involved, or the physical work load.
In view of the above, heart rate monitors have been developed to allow a person to consistently engage in an appropriate quantity and quality of exercise by monitoring the cardiovascular system via the heart rate. In general, effective aerobic conditioning requires that one's heart rate is maintained at a proper level or "target zone" for at least fifteen minutes. Prior to the use of heart rate monitors, a person would have to interrupt the workout in order to manually check their heart rate before continuing or modifying the exertion level of their workout. Of course, the sudden interruption of a workout to check the heart rate is itself disadvantageous.
One known method of monitoring the heart rate uses electrodes attached to the user in the vicinity of the heart. Electrical signals detected by the electrodes are transmitted via conductors or wires to a processor which can compute the heart rate. These "wired" heart rate monitors present various problems in that the wires often interfere with an exercise workout, particularly during running or walking workouts. They are therefore not particularly suited to active exercising.
There have also been developed so-called "wireless" heart rate monitors which use a telemetric transmitter unit for wirelessly transmitting electrical signals detected by electrodes to a separate receiver device. One such telemetric transmitter unit is described in U.S. Pat. No. 5,491,474. It is also known to use wired or telemetric wireless heart rate monitors with stationary exercise devices such as a cycle ergometer as described, for example, in U.S. Pat. No. 5,456,262. The ergometer is used to simulate an exercise program. However, such combined devices restrict the user's exercise routines to stationary exercise units.
Pedometers have also been developed which incorporate pulse meters for sensing the user's heartbeat, such as in U.S. Pat. No. 5,539,706. In contrast to heart rate monitors which determine the heartbeat in beats per minute (bpm) based on electrical signals from the heart, the pulse meters calculate the heartbeat by sensing blood flow through the user's veins. Typically, pulse meters incorporate an infrared light sensor which is pressed against the user's fingertip or clipped against the user's ear. The infrared light sensor determines how fast the user's blood is pumping through their veins. Unfortunately, such pulse meters encounter problems in that if the user's finger is pressed too hard against the sensor, the blood flow will slow down. By contrast, if pressed too lightly against the sensor, then even the slightest movement of the user's fingertip can give erratic readings. Similarly, the ear-clip pulse meter models can also provide faulty readings due to poor circulation in the user's ears, or to sensor movements caused by the connecting wires which must dangle from the sensor. While the use of pulse meters is accurate when the user remains very still, they become unstable and inaccurate during a fitness routine. This therefore defeats the purpose of using the pulse meter to determine the user's heartbeat during exercise. Proper use of heart rate measurement requires that the user be aware of the heart rate during the exercise. As noted above, however, accurate readings with the pulse meters are accomplished by interrupting or slowing down the exercise routine, which has its own disadvantages notwithstanding the fact that the user's heart rate instantaneously lowers during a stoppage or slow down.
There is therefore needed a fitness monitoring device which can effectively provide the user with physiological information concerning their exercise level while at the same time providing empirical information with respect to the duration and extent of a workout.